JP2002326157A - Plate for polishing wafer, and method for machining the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plate for polishing a wafer capable of polishing a wafer to achieve a very high degree of flatness while letting bubbles and particles included in wax escape. SOLUTION: In this plate 1 for polishing a wafer comprising ceramic, a diamond wheel, a blasting device, or an excimer laser device installed on a surface grinding machine is used to machine a wafer application surface 1a for forming groove parts 6 of a width of 30-500 μm and a depth of 15-250 μm at a pitch of 2-10 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing plate capable of polishing a surface of a wafer such as a semiconductor wafer with high precision, and more particularly to a method of processing the polishing plate.

[0002]

2. Description of the Related Art Conventionally, when a plate-like body such as a semiconductor wafer is polished, a plurality of wafers 102 are attached and held with a wax 103 on an attaching surface 101a of a polishing plate 101 as shown in FIG. Then, this polishing plate 1
01 is set on a polishing platen 104 to which a polishing cloth 105 is attached, and a pressing force F is applied to the polishing platen 104 while supplying a polishing agent obtained by adding an alkali or an amine to colloidal silica to the polishing platen 104. Polishing cloth 10
By relatively sliding 5, the surface of the wafer 102 is polished.

[0003] The polishing plate 101 is formed of ceramics such as alumina and silicon carbide.
The attachment surface 101a of the wafer 102 is a smooth surface having a flatness of 5 μm or less (see Japanese Patent Application Laid-Open No. 6-270055).

[0004]

The polishing plate 101 used in the above-described wafer polishing apparatus is:
In order to improve the polishing accuracy of the wafer 102, high flatness and smoothness of the wafer attaching surface 101a are required. In particular, the flatness of the wafer 102, which is a raw material for semiconductor chips, is required to have an accuracy of, for example, quarter micron or less in terms of site flatness on a surface basis, and therefore, the polishing plate 101 is not allowed to be slightly deformed. Therefore, the polishing plate 101 is made of alumina ceramics or silicon carbide ceramics having a low coefficient of thermal expansion.
01 has been improved, and the accuracy of the wafer 102 has been improved.

[0005] However, air may be trapped between the polishing plate 101 and the back surface of the wafer 102 after the wafer 102 is attached, and air bubbles may be formed. When these bubbles are formed, a portion corresponding to the bubbles has an expanded shape on the surface of the wafer 102, and the wafer 1
When polishing No. 02, the inflated portion, that is, the portion corresponding to the filled air bubbles is polished more than the others, and there is a problem that a recess is formed in the polished wafer 102.

The wafer 102 before polishing has been subjected to a flattening process such as lapping or surface grinding. However, a slight amount of warpage, bending, undulation, etc. formed at the time of slicing from the ingot exists, and causes air bubbles to be enclosed. However, there is a limit to the improvement of the shape non-uniformity.

Further, the wax 1 on the back surface of the wafer 102
03 is applied so that the thickness becomes as uniform as possible, but there may be a case where a portion where the thickness becomes thicker is generated. There is a problem that a dent is formed.

The entrapment of air bubbles between the polishing plate 101 and the back surface of the wafer 102 and the formation of a dent in the polished wafer 102 due to the uneven thickness of the wax 103 lead to the deterioration of the flatness of the wafer 102. Improvement is required.

Although it is conceivable to form a groove on the wafer attaching surface 101a of the polishing plate 101 in order to solve the above-mentioned problem, if a groove having a small width and a small depth is to be machined, the residual during the machining is required. There have been problems such as a reduction in the smoothness of the wafer attachment surface due to the stress, a roughening of the inner wall of the groove, and the generation of processing chips due to the shedding of ceramic particles.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended to enclose bubbles between the polishing plate and the back surface of the wafer and to polish the wafer after polishing due to uneven wax thickness. Provides a polishing plate structure that can prevent the formation of dents in the surface, and furthermore, the surface to which the wafer is attached is smooth and has substantially no residual stress, bubbles are unlikely to be trapped, and the wax thickness can be made uniform. It is an object of the present invention to provide a method of processing a simple plate or a method of forming a groove having a small width and a small depth without processing chips.

[0011]

According to the present invention, in a wafer polishing plate made of ceramic, a groove having a width of 30 to 500 μm, a depth of 15 to 250 μm, and a pitch of 2 to 10 mm is formed on the surface of the plate to which the wafer is attached. Is formed.

Further, according to the present invention, substantially no residual stress remains on the wafer attachment surface of the plate, the flatness of the wafer attachment surface is 3.5 μm or less, and the diameter of the groove inner wall is 5 μm.
It is characterized in that there is no machining waste of m or more.

The present invention is further characterized in that the arithmetic mean roughness (Ra) of the inner wall of the groove is 2.0 μm or less.

Further, the present invention provides a method for forming a groove on a wafer-attaching surface of a wafer polishing plate made of ceramics by using any one of a diamond wheel, a blast processing device, and an excimer laser processing device mounted on a surface grinder. It is characterized by.

[0015] Thereby, the air bubbles sealed between the polishing plate and the back surface of the wafer are released into the groove, and the wafer can be polished with a very high flatness.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A is a partial sectional view showing a polishing plate 1 for a wafer 2 of the present invention, and FIG. 1B is an enlarged sectional view showing a main portion of the polishing plate 1 in an enlarged manner. FIG. 3 is a view showing a state in which a wafer 2 is attached to a polishing plate 1 with wax or the like.

The polishing plate 1 of the present invention is made of a flat material, for example, a high-purity alumina or silicon carbide ceramic material, with little mechanical and thermal deformation, and has a plurality of grooves 6 on an attaching surface 1a of the wafer 2. Is formed.

When polishing a silicon wafer or the like using the polishing plate 1, as shown in FIG.
A plurality of wafers 2 are adhered to and held on the attaching surface 1a of the polishing plate 1 with wax 3, and the polishing plate 1 is set on a polishing platen 4 on which a polishing cloth 5 is adhered to the surface. The polishing plate 1 and the polishing pad 5 are relatively slid while the polishing plate 4 and the polishing platen 4 are supplied with an abrasive obtained by adding an alkali or an amine to colloidal silica, so that the surface of the wafer 2 is polished. Has become.

A groove 6 is formed on the attaching surface 1a of the polishing plate 1 of the present invention. Even if air is sealed when the wafer 2 is attached to the polishing plate 1, air is taken into the groove 6. Since air can escape to the outside through the groove 6, the formation of air bubbles can be prevented. Further, even when the thickness of the wax 3 applied to the back surface of the wafer 2 is non-uniform and partially thick, the excess wax 3 flows into the groove 6 to remove the wax 3 in a portion other than the groove 6. The thickness becomes uniform. In this manner, the wafer 2 stuck to the polishing plate 1 of the present invention using the wax 3 is free from partial swelling due to the formation of air bubbles and partial swelling due to uneven thickness of the wax 3. The flatness after polishing is improved.

The groove 6 has a width H of 30 to 500 μm, a depth T of 15 to 250 μm, and a groove pitch P of 2 to 10 mm.

Here, the reason why the width H is set to 30 to 500 μm is that if the width H exceeds 500 μm, there is a high possibility that the shape of the groove 6, particularly the planar shape, is transferred to the wafer 2 during polishing. This is because if the width H is less than 30 μm, the enclosed air and excess wax 3 cannot escape to the groove 6 and the flatness of the wafer 2 deteriorates.

The reason why the depth T is set to 15 to 250 μm is that when the depth T exceeds 250 μm, there is no change in the effect of escaping the enclosed air, but the extra wax 3 escapes to the groove 6. This is because it takes time to remove the wax 3 when the polishing plate 1 is washed, and also requires extra time when processing the grooves, and the residual stress in the grooves may increase depending on the processing method. . vice versa,
When the depth T is less than 15 μm, the sealed air and excess wax 3 cannot escape to the groove 6 and the wafer 2
This is because the degree of flatness is deteriorated.

Further, the reason why the pitch P is set to 2 mm to 10 mm is that if the pitch P exceeds 10 mm, the enclosed air and excess wax 3 cannot escape to the groove 6 and the flatness of the wafer 2 deteriorates. On the contrary, if the pitch P is less than 2 mm, the interval between the groove portions 6 becomes too close, and the adhesive strength of the wafer 2 may be reduced, and the edge of the groove portion 6 is easily chipped.

More preferably, the width H of the groove is 30 to
The flatness of the wafer 2 can be improved by setting the depth to 130 μm and the depth T of the groove to 15 to 80 μm.

As shown in FIGS. 3A, 3B, and 3C, various cross-sectional shapes of the groove 6, such as a square shape, a round shape, and a V shape, can be used. However, as shown in FIG. 4, if processing chips 7 made of degranulated ceramic particles and the like adhere to the inner wall surface of the groove 6, the processing chips 7 cannot be completely removed by washing the plate before polishing. Is
When the wafer 2 is polished, it peels off and causes polishing flaws, thereby lowering the yield. Therefore, it is preferable to minimize the adhesion of the processing waste 7 as described later in detail.

On the other hand, the planar shape of the groove 6 is shown in FIG.
(A) As shown in (B) and (C), various shapes can be used. However, in order to allow the enclosed air and extra wax to escape well, a uniform pattern such as a grid pattern as shown in FIG. Good pattern.

Further, in the polishing plate 1 of the present invention, substantially no residual stress remains on the surface even after the groove 6 is processed, and the flatness of the entire wafer attaching surface 1a is 3.
It is preferable that there is no machining waste 7 having a diameter of 5 μm or more on the inner wall of the groove 6.

Here, the residual stress is a tensile or compressive stress generated on a processed surface when the ceramic is subjected to processing such as cutting, grinding, polishing, and the like. When this residual stress remains in the ceramics forming the polishing plate 1, Due to residual strain and microcracks in the grains and grain boundaries, the plane once processed changes, and finally the flatness of the polishing plate 1 is varied.

For example, when the above-described groove 6 is processed using a diamond pen, a diamond cutter, or the like, residual stress is remarkably left, and even if the polishing is performed by the polishing platen 4 after the processing of the groove 6, the influence is eliminated. And the flatness of the polishing plate 1 cannot be maintained with high precision.

On the other hand, as will be described in detail later, when the groove 6 is formed by using either a blasting device or a laser processing device, no residual stress is generated because no tensile or compressive stress is applied to the processed surface. First, the polishing plate 1 is polished by the polishing platen 4 after the groove 6 is processed.
Can maintain the flatness of the wafer attaching surface 1a at a high accuracy of 3.5 μm or less. Even if machining is performed using a diamond wheel mounted on a surface grinding machine, the influence of residual stress is very small.
It is possible to maintain the flatness of the wafer attaching surface 1a of the polishing plate 1 to an accuracy of 3.5 μm or less by the polishing according to the above.

The processing dust 7 is degranulated ceramic particles generated when the groove 6 is laser-processed and the like, and most of the particles are skipped. It is welded to the inner wall of the groove 6 and cannot be removed even in cleaning after processing.

Here, if processing chips 7 or the like having a diameter of 5 μm or more adhere to the inner wall of the groove 6 and peel off during polishing of the wafer 2, they cause polishing flaws and adverse effects such as lowering the yield. Will be noticeable. Therefore, among laser processing apparatuses, use of an excimer laser processing apparatus that does not generate the processing waste 7 is optimal. It is preferable that the inner wall of the groove 6 does not have the processing chips 7 having a diameter of 1 μm or more, and it is optimal that the processing chips 7 do not exist at all.

The surface roughness of the inner wall of the groove 6 is preferably not more than 2.0 μm in arithmetic average roughness (Ra).
This is because if the thickness exceeds 2.0 μm, the ceramic particles are likely to be shed due to the rough surface, and the above-mentioned processing dust 7 is likely to be generated.

If the groove 6 is machined using the above-mentioned diamond wheel, blasting machine, and excimer laser machine so that no residual stress is generated, the surface roughness of the inner wall is calculated to be the arithmetic average roughness (Ra) 2. 0.0 μm or less. However, if the inner wall of the groove 6 is made too smooth, there is no effect and processing becomes difficult. Therefore, the arithmetic average roughness (Ra) of the inner wall is preferably set to 0.5 μm or more.

After all, when processing the groove 6 having a small width and a small depth as in the present invention, any one of a diamond wheel, a blast processing device, and an excimer laser processing device mounted on a surface grinder is used. It is preferable that substantially no residual stress remains on the wafer attaching surface 1a, the flatness is 3.5 μm or less, and there is no processing chip 7 or the like having a diameter of 5 μm or more in the groove 6. The polishing plate 1 having an arithmetic average roughness (Ra) of 2.0 μm or less can be obtained.

Hereinafter, each processing method will be described. In the processing of the groove 6 in the polishing plate 1 of the present invention, the groove 6
The processing method differs depending on the size of.

For example, in the groove portion 6 where the groove width H exceeds 150 μm, as shown in FIG. 6, by using a diamond wheel 9 mounted on a surface grinding machine, efficient and stable processing accuracy can be obtained. be able to. Specifically, the polishing is performed by fixing the polishing plate 1 to the table 8 and mounting a diamond wheel 9. The tip of the diamond wheel 9 has a radius of about R0.3, and has a processing speed of 8 to 15 m / min. The cut amount per operation is 0.
By processing with a thickness of 02 to 0.04 mm, the groove 6 can be formed with extremely small residual stress. Here, if the cut amount per operation exceeds the above range, non-negligible residual stress is generated, and the diamond is also severely worn and its life is undesirably shortened. Further, the processing waste 7 generated during the grinding processing can be removed by cleaning after the processing.

On the other hand, when the width H of the groove 6 is less than 150 μm, it is difficult to finish the tip of the diamond wheel 9 thinly by machining using the diamond wheel 9. , Stable processing accuracy can be obtained.

In the groove processing by sand blast,
First, the polishing plate 1 is fed by the roller 12 using the laminator shown in FIG. 7A, and the resist film 10 is attached with a thickness of about 50 μm as shown in FIG. 7B. Next, the master pattern 14 is set and positioned in the exposure apparatus of FIG. 8, and exposure is performed by irradiating the light source 13 with ultraviolet rays. When the exposure is completed, the resist 11 in the groove processed portion is removed by development. After the polishing plate 1 is dried, the resist 11 is hardened by post-exposure.

Next, as shown in FIG. 9, the polishing plate 1 is set on the table 8 of the blasting machine, and the grooves 6 are formed by blasting by spraying the abrasive grains 16 from the nozzles 15. The abrasive grains 16 use SiC having a particle size of about 20 μm. As blast conditions, blast pressure is 2.0 to 4.
0 kgf / cm ^2, the moving speed of 30 to 70 mm / min Table 8 carrying the polishing plate 1, the moving speed of the nozzle 15 is preferably carried out at 5 to 20 m / min. For example, blast pressure 2.9 kgf / cm ² , table 8
Moving speed 45 mm / min, nozzle 15 moving speed 1
Process at 1 m / min.

In the processing by sand blast, no lateral stress is applied to the wafer attaching surface 1a, so that no residual stress remains, and the processing dust 7 is blown off by air pressure without being welded to the inner wall of the groove 6, and Does not survive. Therefore, the desired flatness can be ensured even if the polishing by the polishing platen 4 in the groove processing step is omitted or the order is changed, and it is particularly suitable for processing the polishing plate 1 of the present invention.

On the other hand, in the case of the excimer laser processing, as shown in FIG. 10, the polishing plate 1 is placed on the table 8, the positioning and the height are adjusted and set. Processing is performed by irradiating light 18. The processing speed of the excimer laser is 1000-2 when the laser output is 100 W or less.
It is performed by a pulse processing method at 000 mm / min. This is because if the speed is higher than this range, the groove 6 will be disconnected, and a part that cannot be machined will be generated.

In the laser processing, no residual stress remains because no lateral force is applied to the wafer attaching surface 1a. However, in the laser processing method other than the excimer laser, the processing chips 7 are welded to the inner wall of the groove 6 and remain. It is not suitable for processing the polishing plate 1.

Next, an example of a manufacturing process of the polishing plate 1 having the groove 6 according to the present invention will be described.

First, as a material of the polishing plate 1, an alumina ceramic having a purity of 99.5% is used as a ceramic having low thermal expansion, high hardness, high corrosion resistance and high wear resistance. As for the production method, after mixing the respective raw materials at a predetermined ratio, the obtained granules are filled in a molding die composed of a rubber mold, and molded using an isostatic press. The obtained molded body is processed into a predetermined shape by cutting.
After calcination at 00 ° C to remove the binder, about 1700
Baking at ℃ to obtain a plate having an outer diameter of 630 mm and a thickness of 25 mm.

After polishing the obtained polishing plate 1 made of alumina to a certain degree of flatness, the grooves 6 are processed by the various processing methods described above. Then, after polishing by the polishing platen 4, the flatness is measured to confirm that the flatness is the target flatness.

The wafer 2 in the present invention is not limited to a semiconductor wafer, but may be applied to a single crystal substrate such as sapphire, a glass substrate, and other ceramic substrates.

The present invention is not limited to the above-described embodiment, and various changes may be made without departing from the scope of the present invention.

[0050]

EXAMPLES (Experimental Example 1) A wafer 2 was polished using the polishing plate 1 of the present invention and a comparative example, and the flatness of the polished wafer 2 was evaluated.

Using a polishing apparatus shown in FIG. 2, a wax 3 is applied to the back surface of the wafer 2 by spin coating and then fixed to a polishing plate 1, and the polishing plate 1 is attached with a polishing cloth 5 on its surface. The polishing plate 1 and the polishing pad 5 are relatively slid while applying a pressing force F and supplying an abrasive mainly composed of colloidal silica to the polishing platen 4 so as to slide the wafer. 2 was polished.

As shown in Table 1, the polishing plate 1 used for polishing was a conventional grooveless polishing plate 101 (No.
1) and a polishing plate 1 having grooves 6 (No. 2 to No. 2).
22). Here, No. Nos. 2 to 12 are blasted. Reference numerals 13 to 22 denote grooves 6 formed by grinding using a diamond wheel mounted on a surface grinder.

For polishing, the conductivity type is p-type and the resistivity is 10Ω.
Using a silicon wafer 2 (etched wafer) having a diameter of about 200 mm and an etching amount of 10 μm, 140 wafers were polished for each level. The flatness of the polished wafer 2 was measured using a flatness measuring instrument, and the surface undulation (transfer of the shape of the groove 6) was measured with a magic mirror. Table 1
Shows the flatness and the pass rate of the undulation.

[0054]

[Table 1]

From the results in Table 1, No. 21 and 22 are groove widths,
The groove depth is too large, and the surface of the wafer 2 has undulation. In addition, No. 1 using the conventional grooveless polishing plate 101. 1 and No. 1 In Nos. 2 to 5, the groove width and groove depth are not sufficient, and the flatness of the wafer 2 is deteriorated. Also, N
o. In 8, 9, 12, 13, 16, and 17, the groove width and groove depth are good, but the groove pitch is out of the range of the present invention.
And the swell may be deteriorated.

On the other hand, when the groove width, groove depth, and groove pitch are within the range of the present invention, No. 6, 7, 10, 11, 14,
In Nos. 15, 18, and 19, good results were obtained for both the wafer flatness and the undulation.

(Experimental Example 2) Next, as a method of forming the groove 6 of the polishing plate 1, a grinding method using a surface grinder equipped with a diamond pen and a diamond wheel, a blasting method, an excimer laser, a YAG laser, a CO
₍₂₎ The flatness of the polishing plate 1 after the formation of the groove 6 was examined by using the laser processing method, and the wafer 2 was actually polished using these, and the quality of the polished wafer 2 was compared. The polishing was performed using the same wafer 2 as in Experimental Example 1, and the polishing conditions and the evaluation of the wafer 2 were similarly evaluated.
The polishing flaw was visually evaluated under a condensing lamp. Table 2 shows the results.

[0058]

[Table 2]

From Table 2, it was found that the processing with the diamond pen was incompatible with the flatness, groove width, and groove depth of the polishing plate 1, and the wafer quality after polishing was not good. In the case of the YAG laser or CO ₂ laser processing method, processing dust was left in the groove 6, which caused polishing scratches on the surface of the polished wafer 2.

On the other hand, in the case of grinding using a surface grinder equipped with a diamond wheel, blasting and excimer laser processing, good results can be obtained in both the quality of the polishing plate 1 and the wafer 2. Was. As the processing method of the groove 6, the blast processing method is the most excellent in consideration of the apparatus cost and the wafer quality after polishing comprehensively.

The polishing plate of the present invention is used not only for polishing a semiconductor wafer such as silicon or a compound semiconductor but also for polishing a plate-like work requiring a high flatness, such as a quartz substrate, a glass substrate or a magnetic disk substrate. It is possible.

[0062]

As described above, according to the present invention, in a wafer polishing plate made of ceramics, a width of 30 to 500 .mu.m and a depth of 15 to 25
By forming the groove having a pitch of 0 μm and a pitch of 2 to 10 mm, air sealed between the polishing plate and the back surface of the wafer can be released into the groove when the wafer is attached to the polishing plate, and the air becomes bubbles. In addition to this, the excess wax can be released into the groove, so that the dent generated in the polished wafer can be reduced, and the flatness can be improved.

The grooves are formed on the surface of the wafer polishing plate made of ceramics by using any one of a diamond wheel, a blast processing device, and an excimer laser processing device mounted on a surface grinding machine. 2. Substantially no residual stress remains on the wafer attachment surface of the plate, and the flatness of the wafer attachment surface is 3.
It is possible to provide a polishing plate having a flatness of 5 μm or less and having a flatness with high precision without the presence of processing chips having a diameter of 5 μm or more on the inner wall of the groove.

Therefore, by using the polishing plate of the present invention, the polishing accuracy of the wafer can be improved, and the wafer can be processed with a high yield.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing a polishing plate for a wafer of the present invention, and FIG.

FIG. 2 is a sectional view showing a use state of the polishing plate of the present invention.

FIGS. 3A, 3B, and 3C are enlarged cross-sectional views of main parts showing grooves of a plate for polishing a wafer of the present invention.

FIG. 4 is an enlarged cross-sectional view of a main part showing a state in which processing dust and the like are attached to an inner wall surface of a groove.

5 (A), 5 (B) and 5 (C) are flatness diagrams showing a wafer polishing plate of the present invention.

FIG. 6 is a schematic view showing a method for processing the polishing plate of the present invention using a surface grinder.

FIGS. 7A and 7B are schematic views showing a resist attaching step using a laminator in the polishing plate processing method of the present invention using a blast processing apparatus.

FIG. 8 is a schematic view showing a step of exposing a resist by an exposure apparatus in a method of processing a polishing plate of the present invention by a blast processing apparatus.

FIG. 9 is a schematic view showing a method for processing the polishing plate of the present invention using a blast processing apparatus.

FIG. 10 is a schematic view showing a method for processing a polishing plate of the present invention using an excimer laser processing apparatus.

FIG. 11 is a sectional view showing a conventional polishing plate.

[Explanation of symbols]

 1, 101: Polishing plate 1a, 101a: Adhering surface 2, 102: Wafer 3, 103: Wax 4, 104: Polishing plate 5, 105: Polishing cloth 6: Groove H: Width T: Depth P: Pitch 7 : Processing waste 8: Table 9: Diamond wheel 10: Resist film 11: Resist 12: Roller 13: Light source 14: Master pattern 15: Nozzle 16: Abrasive grain 17: Laser oscillation port 18: Laser light F: Pressing force

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/304 622 H01L 21/304 622J (72) Inventor Akira Miyashita 150 F Shin-Etsu Semiconductor Shirakawa Plant F-term (reference) 3C049 AA07 AB04 CA01 CB01 CB02 3C058 AA07 AB04 CA01 CB01 CB02 DA17 4E068 AD00 CA02 CA15 DA00 DB12

Claims (7)

[Claims] 1. A wafer polishing plate made of ceramics having a width of 30 to 500 μm on a wafer attaching surface.
m, a groove having a depth of 15 to 250 μm and a pitch of 2 to 10 mm. 2. The method according to claim 1, wherein substantially no residual stress remains on the wafer attachment surface, the flatness of the wafer attachment surface is 3.5 μm or less, and there is no processing waste having a diameter of 5 μm or more on the inner wall of the groove. 2. The wafer polishing plate according to claim 1, wherein: 3. The arithmetic mean roughness (Ra) of the inner wall of the groove is 2.0 μm or less.
2. The wafer polishing plate according to 1. 4. A groove is formed on a wafer attachment surface of a wafer polishing plate made of ceramics by using any one of a diamond wheel, a blast processing device, and an excimer laser processing device mounted on a surface grinding machine. Processing method of the wafer polishing plate to be used. 5. A groove is formed using a diamond wheel mounted on a surface grinding machine at a processing speed of 8 to 15 m / min and a cut amount per stroke of 0.02 to 0.04 mm. A method for processing the wafer polishing plate according to the above. 6. Using a blasting machine, a blast pressure of 2.0 to 4.0 kg / cm ² and a table moving speed of 30 to
70 mm / min, nozzle movement speed 5.0-20.0 m
5. The method for processing a wafer polishing plate according to claim 4, wherein the groove is formed at a rate of / min. 7. An excimer laser processing apparatus, wherein a laser output is 100 W or less, and a laser processing speed is 1000-2.
5. The method for processing a plate for polishing a wafer according to claim 4, wherein the groove is formed at 000 mm / min.